The present invention relates to a two stage alarm system for alerting septic tank owners of high sludge levels and the need for cleaning and/or pumping the septic tank.
Septic systems generally comprise a septic tank and effluent disposal field interconnected by piping. The effluent disposal field comprises perforated pipes embedded in gravel and buried beneath the surface of the earth. Effluent fluids pass from the septic tank through the interconnecting pipe and to the effluent disposal field, where the fluid leaches into the surrounding gravel and earth.
The problem which generally causes clogging of the septic system is what can be referred to as "suspended solids" in the effluent. These suspended solids are almost invisible in the effluent and are located in the septic tank fluid between the layer of solids at the bottom of the tank and the outlet pipe to the effluent disposal field. As the layer of solids on the bottom of the tank become deeper, as it will in time, the layer of suspended solids is moved upwards into a more concentrated area in the tank. Eventually, the suspended solids move along with the effluent out of the septic tank through the interconnecting piping into the effluent disposal field and begin the process of clogging the system.
In order to alert owners of high sludge levels in the septic tank, and prevent the undesirable passage of rising sludge into the drain field or leach bed, the prior art has attempted to provide various systems to alert home owners, or other septic tank users, of unsatisfactory sludge levels in the septic tank. Several of such prior art systems are reflected in the following U.S. Patents:
a.) U.S. Pat. No. 3,923,655, to McKinney, teaches a system for determining the sludge level in a secondary sedimentation tank of a sewage treatment system. The temperature differential between the sludge layer and the supernatant is used to detect the sludge level. In response to a differential temperature indicating a predetermined level of sludge in the tank, some of the sludge is wasted. PA1 b.) U.S. Pat. No. 3,954,612, to Wilkerson, is directed to an above ground septic tank indicator, which indicates the water level in the tributaries leading from the tank so that any excess water therein may be pumped out before it causes a back up of sewage upstream of the septic tank. PA1 c.) U.S. Pat. No. 4,319,998, to Anderson, relates to a monitor for an effluent disposal system for preventing suspended solids in an effluent from clogging a disposal field. A separate monitor housing having an inlet and an outlet is installed in the piping interconnecting a septic tank to a disposal field. A screening system in the housing screens out suspended solids. As the solids accumulate on the screening system over a period of time, the fluid level raises, actuating a float operated switch connected to means to signal that the system needs servicing. An additional float operated switch can be provided for indicating saturation of the disposal field. PA1 d.) U.S. Pat. No. 4,348,278, to Caccia, teaches a monitoring arrangement for settlement tanks to permit determination of the prevailing distribution of suspended matter, including that depth of the lighter liquid at which an interface may exist with settled material of greater density, to permit selective removal of one of the fluids from the tank, for utilization or disposal. The monitoring arrangement comprises a probe displaceably mounted for movement downward through the liquid having detection means for sensing the instantaneous hydrostatic pressure acting on the head of the probe. One embodiment utilizes a display wherein the variation in density is evidenced as a change in the gradient of a pressure depth and/or pressure time characteristic. The provision of depth monitoring means for the probe head permits the provision of a subtractive feed back to compensate for the static head of the parent fluid, which by subtraction from the sensor head output provides a differential output responsive solely to variation in sensed pressure due to the presence of settling suspended matter creating a density change of the tank contents at the level being sensed. PA1 e.) U.S. Pat. No. 4,715,966, to Bowman, is directed to a septic tank sludge level indicator including a float assembly that can be inserted downwardly into a septic tank through a permanently installed introducer tube or access pipe that has an upper end substantially flush with ground surface and provided with a removable cap for insertion and removal of the float. The float is constructed so that it will not be buoyant in a liquid material or floating scum on the upper surface of liquid material normally found in a septic tank but will be supported when the float comes into contact with collected sludge in the bottom portion of the septic tank with the upper end of the float assembly including indicia indicating the depth of sludge in the septic tank thereby providing an indication as to whether the sludge should be pumped from the tank.
While the prior art offers some solutions to the need for an alarm mechanism to alert a home owner, for example, of a rising level of sludge with the owner's septic tank, none appear to present a system that includes a dual alarm system, i.e. first a caution, then a critical alert, in the manner of the present invention. The manner by which this invention meets the desired goal hereof will become apparent to those skilled in the art from a reading of the following specification in conjunction with the various drawing.